Pneumatic jack



' April 17, 1934- P. M. KELLY PNEUMATIC JACK Filed Nov. 6. 1930 INVENTOR EMK-z WITNESS ATTORNEY the ring 21 in position.

Patented Apr. 11, 1934 t t 1,955,635 l UNITED STATES PATENT oFFlcE PNEUMATIC JACK Pascal M. Kelly, El Paso, Tex. Application November 6, 1930, Serial No. 493,881 2 claims. (c1. 254-93) My invention relates to pneumatic jacks and The piston 14 is elevated through any suitable it consists in the constructions, arrangements source of air under pressure and as shown,.air and combinations herein described and claimed. enters the cylinder 13 at 27 through a pipe 28.

It is an object of my invention to provide a Air is supplied to the pipe 28 through the valve pneumatic jack in which an eincient air seal is 29. An air release valve 30 is associated with the effected between the cylinder and piston. pipe 28, so that by opening the valve 30 air will be It is a further object of the invention to provide permitted to escape and the jack will be lowered. means upon the piston which coacts with the The operation of the jack will be apparent. head of the cylinder for effecting an air tight Air admitted through the pipe 28 will raise the seal, thus obviating any possibility of lowering piston 14 upwardly until the bevelled face 19 of 65 of the jack through leakage of air passing the the piston 14 engages the bevelled face 22 of the piston. y packing ring 21 and exerts such force as to com- Additional objects, advantages and features of press the ring 21, producing a tight joint between the invention will be apparent from the following the contacting bevelled faces. Thus, if any air description considered in conjunction with ythe should leak past the cup 16 the snug contact be'- tm accompanying drawing, wherein: y tween the abutting faces of the piston and pack- Figure 1 is a top plan view of a jack constructed ing Will prevent passage 0f alrfabOVe the Pisten in accordance with my invention. 14, and thereby positively retain the jack in ele- Figure 2 is a vertical sectional view thereof Vated pOSitOn. illustrating the piston and packing. In the form shown in Fig. 3, the cylinder '13s is Figure 3 is a fragmentary detail illustrating a, constructed as before described with the excepmodifled form of packing. tion that the annular recess and packing ring is There is illustrated a pneumatic jack generomitted. The piston head 15a is of lesser diamally indicated by the reference character 10, eter than the metallic retaining Cup 17 and has which may be of any well known construction, Aan annular IOWeI face rounded as at 31L A Cup 80 y embodying a wheeled frame 11 and draft tongue washer 32 is secured upon the head 15a by the 12, metallic cup 1'1n and screw 18, as before de- A cylinder 13 is mounted in any desired manscribed. ner upon the frame l1 and reciprocable within The cup washer in the present instance, comthe cylinder there is a piston 14. The piston inprises a main bedy 33 having a downwardly prO- 85 cludes a head l5 upon which there is secured a leeting eentinuous flange 34 and upwardly preleather packing cup 16 retained in position by a jeeting rim 35. The rim 35 is quite thiek and is suitable metallic cup 17 and screw 18, compressed lbetween the rounded lower face of The head 15 of the piston has a, beveued cirthe piston head 15 and the metallic washer 1'7". cumferential face 19 for a purpose to be explained The rim 35 projects abOVe the upper faee 0f the hereinafter. piston head and is adapted to engage within an The upper part of the cylinder 13 is provided annular groove 36 formed in the underside of with an annular recess 20 within which there is the Cap 23- disposed a compressible packing ring 2l. The In this ferm 0f packing, it Will be apparent packing ring 21 projects beyond the recess 20 and that When the piston 14' l5 forced t0 its fluter- 95 the interior of the ring is provided with a bevelled mOSt pesitien, the rrn 35 0f the pistOn vWill be face 22, complemental to the face 19 to the piston compressed in the annular ErOOVe 36. thus effeehead 15. tively sealing the piston against leakage of air 'I'he cylinder 13 is screw threaded at its upper there-pasty end and receives a cap 23 for closing the cylinder. WithOut further, description it iS thought that 100 If desired a metallic washer 24 may be interposed the features and advantages of the invention will between the cap 23 and ring 21, to securely retain be readily apparent t0 these Skilled in the art. v and it will be, of course, understood that changes The cap 23 is centrally apertured to receive in form, proportion and minor details of the conthe piston rod 25 slidably therethrough, as shown. struction may be resorted t0, WlthOut departing 105 The piston rod is hollow and is interiorly threadfrOrn the Spirit 0f the inventlen 0r 0f itS Scope as ed for reception of a threaded jack head 26. By claimed. this construction, it will be apparent that the I claim: jack head 26 may be adjusted vertically, as de- 1. In a pneumatic jack, a cylinder, a cap for sired. closing the upper end of the cylinder. the upper no having an inwardly bevelled face, a packing ring secured between said recess and cap and free of contact with said piston, said ring projecting inwardly from said cylinder a short distance and having an inwardly bevelled face complemental to the bevel face of said head, whereby to eiect an airtight seal between said head and said ring at times.

PASCAL M. KELLY. 

